Idiopathic and Spontaneously Regressing Thrombus in Right Renal Vein and Inferior Vena Cava

We present the case of a 57‐year‐old woman with a thrombus in the right renal vein and the inferior vena cava that disappeared spontaneously during 6 months of observation. She had no thrombus‐related disease such as kidney cancer, dehydration, multiple myeloma, nephrotic syndrome, or abnormal coagulability. While various examinations were being performed over a 2 month period the thrombus regressed spontaneously. After 6 months of follow‐up the thrombus could not be seen on abdominal computerized tomography scan. Twenty months after disappearance of the thrombus the patient is doing well and has no recurrence of thrombus.